Kot9: Shield room (SPOILER)

[BrillOShea]

I'm in the Shield room trying to figure out the puzzle. A previous post says that the chest on the will have some items in it that I then need to put into the chests around the room. But my problem is that there is nothing in the main chest onthe stairs. I've stood on the plate, waited a couple hours then stood on the plate, waited a couple hours, then tried to open it without stepping on the plate. I've tried to leave the room and come back, but the door is locked.
PLease help!
Thanks